This invention relates to well bore testing methods and apparatus employing a new and improved pressure-actuated full-bore reversing valve arranged to be tandemly coupled to a packer and a pressure-actuated test valve which, when the tools are suspended in a well bore from a pipe string, is selectively operated in response to successive changes in the pressure differential between the interior of the pipe string and the well bore annulus for carrying out a series of test operations. More particularly, the present invention relates to a new and improved full-bore reversing valve having reversing ports which initially are kept closed for blocking communication between the well bore annulus and the interior of the pipe string until a predetermined number of these pressure differential changes have been applied to the reversing valve. Thereafter, the next change in the pressure differential is effective for selectively opening the reversing ports and a subsequent pressure differential change will then reclose the ports thereby readying the new and improved tool for a second operating cycle should it be desired to conduct additional testing or completion operations before the string of tools is removed from the well bore.